Chinese Long March 4B lofts Shijian-16 satellite

The Chinese have conducted another surprise launch, this time orbiting the Shijian-16 satellite via the Long March-4B (Chang Zheng-4B) rocket. The launch took place from the Jiuquan Satellite Launch Center at 03:50 UTC on Friday, lifting off from the 603 platform at Launch Complex 43.

Chinese Launch:

The launch was not scheduled on official manifests, with only hints as to what the mission may involve on Chinese forums. Following launch, state media did confirm the satellite will be used for “space environment measurements and technology testing”.

For the last few months, specialists noted they were waiting for the launch of a new pair of Shijian-6 class satellites. However, state media reports confirm that this launch may be the follow-on to the SJ-6 series.

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Shijian-6 was a series of scientific satellites in which each mission was composed of two satellites designed for space scientific experiment.

Lofted by a single launch vehicle, Satellite A was developed by SAST while Satellite B was developed by China Spacesat Co Ltd of CAST. The onboard mission payload was developed by China Electronic Technology Group Corporation.

This was the first use of the Long March-4B from Jiuquan.

The Long March-4B launch vehicle:

The feasibility study of the CZ-4 Chang Zheng-4 began in 1982 based on the FB-1 Feng Bao-1 launch vehicle. Engineering development was initiated in the following year. Initially, the Chang Zheng-4 served as a back-up launch vehicle for Chang Zheng-3 to launch China’s communications satellites.

After the successful launch of China’s first DFH-2 communications satellites by Chang Zheng-3, the main mission of the Chang Zheng-4 was shifted to launch sun-synchronous orbit meteorological satellites. On other hand, the Chang Zheng-4B launch vehicle was first introduced in May 1999 and also developed by the Shanghai Academy of Space Flight Technology (SAST), based on the Chang Zheng-4.

The rocket is capable of launching a 2,800 kg satellite into low Earth orbit, developing 2,971 kN at launch. With a mass of 248,470 kg, the CZ-4B is 45.58 meters long and has a diameter of 3.35 meters.

SAST began to develop the Chang Zheng-4B in February 1989. Originally, it was scheduled to be commissioned in 1997, but the first launch didn’t take place until late 1999. The modifications introduced on the Chang Zheng-4B included a larger satellite fairing and the replacement of the original mechanical-electrical control on the Chang Zheng-4 with an electronic control.

Other modifications were an improved telemetry, tracking, control, and self-destruction systems with smaller size and lighter weight; a revised nuzzle design in the second stage for better high-altitude performance; a propellant management system for the second stage to reduce the spare propellant amount, thus increasing the vehicle’s payload capability and a propellant jettison system on the third-stage.

The first stage has a 24.65 meter length with a 3.35 meter diameter, consuming 183,340 kg of N2O4/UDMH (gross mass of first stage is 193.330 kg). The vehicle is equipped with a YF-21B engine capable of a ground thrust of 2,971 kN and a ground specific impulse of 2,550 Ns/kg. The second stage has a 10.40 meter length with a 3.35 meter diameter and 38,326 kg, consuming 35,374 kg of N2O4/UDMH.

The vehicle is equipped with a YF-22B main engine capable of a vacuum thrust of 742 kN and four YF-23B vernier engines with a vacuum thrust of 47.1 kN (specific impulses of 2,922 Ns/kg and 2,834 Ns/kg, respectively).

The third stage has a 4.93 meter length with a 2.9 meter diameter, consuming 12,814 kg of N2O4/UDMH. Having a gross mass of 14,560 kg, it is equipped with a YF-40 engine capable of a vacuum thrust of 100.8 kN and a specific impulse in vacuum of 2,971 Ns/kg.

Launch Site:

The Jiuquan Satellite Launch Center, in Ejin-Banner – a county in Alashan League of the Inner Mongolia Autonomous Region – was the first Chinese satellite launch center and is also known as the Shuang Cheng Tze launch center.

The site includes a Technical Centre, one Launch Complexes (LC43) with two launch platforms and a Launch Area for the launch of the solid fuel Kuaizhou launch vehicle, Mission Command and Control Centre, Launch Control Centre, propellant fuelling systems, tracking and communication systems, gas supply systems, weather forecast systems, and logistic support systems.

Jiuquan was originally used to launch scientific and recoverable satellites into medium or low earth orbits at high inclinations. It is also the place from where all the Chinese manned missions are launched.